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<head>
  <meta charset="UTF-8">
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  <title>Document</title>
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<body>
  <script>
    function Person(name,age) {
      this.name = name
      this.age = age
    }
    Person.prototype.eat = function(){
      console.log('eat');
    }

    function Student(name,age,id){
      Person.call(this,name,age)
      this.id = id
    }
    Student.prototype = new Person
    Student.prototype.constructor = Student
    Student.prototype.study = function () {
      console.log('study');
    }
    const s1 = new Student('xm',18,99)
    console.log(s1,'s1');
    // function Person(name,age){
    //   this.name = name
    //   this.age = age
    // }
    // Person.prototype.eat = function(){
    //   console.log('eat');
    // }
    // function Student(id,name,age){
    //   Person.call(this,name,age)
    //   this.id = id
    // }
    // Student.prototype = new Person
    // Student.prototype.constructor = Student
    // Student.prototype.study = function(){
    //   console.log('study');
    // }
    //父类 基类
    // function Person(name, age) {
    //   this.name = name;
    //   this.age = age;
    // }
    // Person.prototype.eat = function () {
    //   console.log("eat")
    // }

    // //子类
    // function Student(id, name, age) {
    //   //构造函数继承
    //   Person.call(this, name, age);
    //   this.id = id;
    // }

    // //原型链继承(不能直接把父类的原型对象赋值给子类的原型对象,否则会共享)
    // Student.prototype = new Person;
    // //修正constructor
    // Student.prototype.constructor = Student;

    // Student.prototype.study = function () {
    //   console.log("node")
    // }
  </script>
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